1) no, and as noted earlier, you will not be connecting direct to the battery. Those fuses are for protecting the amp, not the supply cables.
2) if you are referring to the ANL style fuse that bridges from the ACC B+ cable to the amp wall accessory BUS?
3) If you are referring to the B+ that runs from the switch to the ANL fuse mounted on the amp wall? That wire is gauged for factory loads, with maybe a little to spare. They did not factory in customer installed options. Using any factory wiring or terminating to anything factory, you have to use your specific load values.

Thats a 5 chnl amp. Are there plans to make use of the woofer chnl? The factory amp is capable of 400W to a 2 ohm woofer. Factory woofer is a 4 ohm, so only receiving 200W. That amp is only going to deliver 250W rms to each Rev-10.